1. Field of the Invention
The invention relates to power supplies and, more particularly, to an arrangement having parallel-connected DC power supply units, the power supplies of which each generate a partial output current for supplying a load with an overall output current. The invention further relates to a DC power supply unit which is suitable for use in such an arrangement.
2. Description of the Related Art
DE 10 2005 014 992 A1 discloses an arrangement, which is particularly suitable for use in automation technology. In such an arrangement, the respectively available output of the power supply units, which are provide to supply power to a load, is ideally added to form a total power. In the event that one of the parallel-connected power supply units is switched on first, it is highly likely here that this is overloaded since the total power for supplying the load exceeds the output of this power supply unit. As a result of the overload, the power supply unit switches off. Moreover, in the event that a further power supply unit of the arrangement is switched on during the switching off of the power supply unit and/or after it has been switched off, the further power supply unit also switches off due to the overload.
To largely prevent the power supply units, which are fed from a mains power supply and/or from a current source, from switching off, a shared switch can be provided, to which all power supply units are connected simultaneously. However, as the power supply units usually have different start-up characteristics, particularly due to a shared use of available power supply units with newly developed “compatible” power supply units, an overload during the start-up cannot be prevented. Furthermore, it is also difficult to use different current sources as energy sources of the respective power supply unit or to connect power supply units with different outputs and/or start-up characteristics in parallel.